This is interesting because Stalwart has a built-in clustering feature and can use distributed databases as its storage layer, so you get high-availability opti

This is interesting because Stalwart has a built-in clustering feature and can use distributed databases as its storage layer, so you get high-availability options out of the box. I've struggled with doing similar HA on Dovecot, never quite being true HA (for the open source version of Dovecot) for a while and never found a good other open source option.